US3088914A

US3088914A - Fire-resistant hydraulic fluids

Info

Publication number: US3088914A
Application number: US18841A
Authority: US
Inventors: Rudolf J Holzinger
Original assignee: Socony Mobil Oil Co Inc
Current assignee: ExxonMobil Oil Corp
Priority date: 1960-03-31
Filing date: 1960-03-31
Publication date: 1963-05-07
Anticipated expiration: 1980-05-07
Also published as: GB982372A

Description

United States Patent 3.0885914 FIRE-RESISTANTjHYDRAULIC FLUIDS Rudolf J. Holzinger, NortbMerriclr, N.Y., assignor to SYOCOkHY Mobil ,Oil Company, Inc, acorporation of New or No Drawing. FiledMar, 31, 1960, Ser. No. 18,841 4 Claims. (Cl. 252-76) This inventionrelatesto an improved composition for use in-hydraulic systems and'is particularly concerned withan improved water-in-oil emulsion useful as a fireresistant hydraulic oil.

I-Iydraulicsysterns are being employed more and more extensively in industry-to operate machinery from remote locations and with comparative ease. Various types of liquids have been employed as the operative fluidin these hydraulic systems; however, for one reason or another, these liquids have been found to lack required properties. Various oils, such as mineral oils, have found muchfavor in the past; however, many applications of hydraulic systems cannot tolerate leaks with such a pressure transmitting medium since the oil,- under high pressure, may then find its way to heat and flame where explosion or combustion occurs. Hydraulic systems are used in metalworking and treating plants and leaks in the system have caused serious accidents in the past.

Water-in-oil emulsions have been tried in the prior art to provide a useful hydraulic oilthat had the benefit of poor flammability. While the emulsion remains unbroken with the water uniformly dispersed throughout the oil in the form of'fine particles, the fire resistance is high but adequate stability of the 'emulsion has not been presentin prior formulations. The water particles tend to agglomerate in clusters and to settle to the lower part of the reservoir, thereby impairing the fire resistance of the fluid remaining in the upper part. In some cases, an upper layer of clear oi-l possessing no fire resistance whatsoeverwill result. In more severe cases, the water may coalesce into larger droplets which eventually will settle out and form a layer of free water on the bottom. In addition to impairment of fire resistance the latter condition is objectionable in that free water may enter the circulating system and may cause corrosion of lines and working parts and rapid wear of pump parts due to lack of lubrication.

An object-of this invention is to provide an improved composition for use as a hydraulic oil.

An additional object of this invention istopro-vide an improved composition having fire resisting properties for use as a hydraulic oil.

An additional object'of this invention is to provide an improved stable water-in-oil emulsion having fire-resista.

ing properties for. use as a hydraulic oil.

These and other important objects will be made ap-.

parent in the ensuing detailed discussion of this invention.

I have found that a stable, fire-resistant water-in-oil emulsion of low viscosity can be obtained by emulsifying up to percent water with an. oil, using calcium sulfonate-as thebasic emulsifier. and further using a combina tion of selected calcium salts of aliphatic acids and selected calcium salts of naphthenic acids as a stabilized medium, The salts or soaps. of. other metals, such as barium, magnesium, strontium, manganese, zinc, aluminum, cadmium, tin-, chro mium and cobalt, may. also be used although calcium. is; prefer-red,

The oil used may be any suitablehydrocarbon oil of viscosity. rangefrom-nabout 50 -74001-SayboltUniversal' seconds at 100 E. .Ithas been. found, however, that a white oil in that viscosity rangeprovidesunusually good results whenusing-the emulsifying and stabilizing agents of C or lessbeing disclosed hereinafter. This is a completely unexpected result since the rigorous refining required to produce white oils is generally conceded to removenatural inhibitors and reduce lubricity. However, when awhite oil is used as the base oil of the emulsion of this invention, improved oxidation resistance and improved emulsion stability are obtained. This can readily be, demonstrated by making a suitable oxidation test on the emulsion using a naphthenic base oil, a paraflinic base oil and a white oil. as the baseoil. The test comprises primarily submitting four different metals to submersion in the. oil for 40 hours at 210 F. while .air or oxygen saturated with water vapor is bubbled through the test bath. The. naphthenic oil clearly shows signs of poor oxidationstabilitywhile the paraifin oil clearly shows signs of poor emulsion stability. On the contrary, the emulsion made using white oilas the base oil shows good oxidation and good emulsion stability. This is clearly a result thatcou-ld not be predicted from prior knowledge.

The calcium sulfonate used as the basic emulsifier may be present in the blendin the amount of about .252.50 percent by weight of the total-blendbutpreferably about .3-1.0 percent by Weight can be used to provide entirely satisfactory results. The calcium .sulfonate, while primarily anemulsifying agent, supplies a certain amount of anti-corrosive action and anti-wear protection. The calcium sulfonate should have a molecular weight of at least-about 900. When the calcium sulfonatehas a molecular weight of about 1000 the emulsification is excellent. It is found that the emulsion will gradually deteriorate when calcium sulfonate is used alone and hence the mixture of calcium sulfonate and oil alone as. a hydraulic oil is not satisfactory. However, unusually stable emulsions are found to occur when the calcium salts of naphthenic acids are used asa stabilizing medium. The molecular weight of the naphthenic acid is found to be critical, naphthenic acids ofniolecular weight less than 315 being found to possess little or no stabilizing action. In fact, in many cases, acids below the critical limit of'molecular weight act as emulsion breakers. Particularly useful in this invention are napththenic acids of about 315-1000 molecular weight. A preferred range of molecular weight of naphthenic acids is 315-500 Outstanding results are obtained with naphthenic acids identified as Sunaptic B and Snnaptic C. The B acid has a molecular weight of.325 whereas the C acid has a mo lecular weightpf 4-15. The Sunaptic acid can be obtained from the Sun Oil Company of Philadelphia, Pennsylvani'a.

The emulsion can also be stabilized by adding the calciumsalts of. aliphatic acids (both saturated and unsaturated) as a stabilizing medium. The length of the acid chain is found to be critical, acids having a. chain length i found to possess little or no stabilizing action when used as the sole stabilizer. Particularly useful are aliphatic acids (saturated or unsaturated) of a chain length of broadly about C -C and preferably about C C Outstanding results are obtained with behenic acid -(C Outstanding results can also be o tained with erucic acid (unsaturated C acid).

When the 'twostabilizing materials described above are used simultaneously improved results are obtained since these materials show a synergistic action in this environment. The calcium salts of aliphatic acids of a carbon chain length broadly about C -C and preferably about C C work synergistically with the calcium salts of naphthenic acids of molecular weight about 315- 1000 and preferably 315-500 to provide an unusually stable and preferred hydraulic fluid. The two agents may be combined in any proportion to provide a combined :situ.

3 stabilizing agent. Each agent should broadly vary be tween about .10 to 2.50 by weight and preferably about 0.2 to 1.0 by weight of the finished blend. Excellent results are obtained by using equal amounts by Weight the solution or dispersion rapidly with the oil containing the calcium sulfonate and aliphatic acid with high-speed agitation. Generally, the water phase is added to the oil phase, although in some cases the opposite method of the calcium salt of behenic acid and the calcium may be preferred. The resultant emulsion may be subsalt of Sunaptic C, although unequal amounts may be jected to further mechanical treatment such as passing successfully used. it through a colloid mill or homogenizer. A suitable While stability of the emulsion is an important feamethod of preparation is as follows: The calcium sulture, it is also highly desirable to control its viscosity. fonate, the aliphatic acid and the naphthenic acid are If the emulsion is too viscous, it may not function in dissolved in the oil and the mixture is heated to 175:5 some hydraulic machinery. This is especially important F. the water is heated to 175i5 and the lime, after at ambient temperature, e.g. at start-up. If the emulsion being added to the water, is kept in dispersion by mild is too viscous, it may fail to flow properly under the sucagitation. The water phase is then added to the oil phase tion provided by the pump. In such a case, the pump under vigorous agitation, using a high-speed mixer, fol- Would not be provided with an adequate volume of 1 lowed, if necessary, by further mechanical treatment fluid and cavitation would occur, with the possibility of such as passing the emulsion through a colloid mill or damage to the working parts of the pump. Therefore, homogenizer. In some cases, it may be desirable to also it is desirable to hold the viscosity of the emulsion form the calcium sulfonate in situ. In this instance, all Within certain limits. In applications such as here conthree acids, namely, the sulfonic acid, the aliphatic acid templated, it is frequently desired to hold the viscosity and the naphthenic acid, are dissolved in the oil, with the below 400 S.U.S. at 100 F. or preferably at or below subsequent steps remaining substantially unchanged. 350 S.U.S. at 100 F. It is desirable .and in many cases essential that the I have found that emulsions of suitable viscosity charamount of lime to be used in preparing these emulsions acteristics can be prepared by using calcium sulfonate be sufiicient to form the basic soaps of the alphatic and in combination with both the calcium soaps of selected naphthenic acids and also, if a neutral calcium sulfonate naphthenic acids, such as the naphthenic acids described is used, to convert the latter to the basic sulfonate. Freabove, and the calcium soaps of certain fatty acids. The quently, it is desirable toemploy an amount of lime in fatty acid may have a chain length of from about 16 excess of the stoichiometric ratio necessary to produce to about carbon atoms. both the basic soaps and the basic sulfonate. This ex- Many emulsions used in industry are maintained in 30 cess may, for instance, amount to 50 percent above the a stable state by means of high viscosity which interferes stoichiometric ratio and may be as much as l00 percent with separation of the oil and/or water phases. The or more. more fluid the preparation, the more difficult it becomes Rating of emulsion stability may be done visually to preserve the initial state of the emulsion. Therefore, either at room temperature or after storage at elevated it is exceedingly valuable to be able to produce an emultemperature, e.g., 170 F. A convenient method consists sion that exhibits both features, i.e. high stability and of storing the emulsions in.100 ml. graduated cylinders low viscosity. This is particularly true when stability so that the volume of oil or Water separated may be at high temperatures While maintaining low viscosity is read directly as percent of total volume. Obviously, it desired. In this respect, the calcium salts of aliphatic is desirable to keep separation of oil and water to a acids (saturated or unsaturated) of a chain length of minimum. Separation of water is particularly objectionbroadly about C C and preferably about O -C are able since it indicates coalescence of the dispersed phase. again outstanding. The examples given in Table I, shown below, demon- In order to insure adequate fire protection, a sufiicient strate the magnitude of improvement brought about by amount of Water must be properly emulsified into the this invention. a

Table 1 [Parts by Weight] I Examples 1 2 3 4 5 6 7 8 Nut. Calcium summits, 1,000 M.Wt.100-|- Active 1.0 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Stearic Acid. hi it fieitiianiarnut if. "if? imghthenicAcidZ15MI Wt r 0.5 0.25 0. 25 0.25 140 U.S.P. White 0i1 .5 .5 .5 8.5 18.5 18.5 18.5 90"U.S.P. White Oil .0 .0 .0 0.0 40.0 40.0 40.0 Antioxidant .5 .5 .5 0.5 0.5 0.5 0.5 Lime' .2 .2 .2 0.2 0.2 0.2 0.2 Waugh .0 .0 .0 .o' 0.0 40.0 40.0 40.0 Viscosity, S.U.S. @100 F 337 481 486 357 354 345 343 315 i aigi gi iti F Separation' tig ifggigni ij... i3 3 3 i i i 7 days epara on 1 8 %%rf'%l55iiii -1} 33 iii i3 9 3 S 1 Homogenized 4500 p.s.i. 2 Complete separation.

oil. The Water may range from about l0-50 percent .of the water-in-oil emulsion; however, a fully acceptable emulsion having excellent fire-resisting properties is obtained when the water is about l0-40 percent of the water-in-oil emulsion.

In preparing the emulsions of this invention it has been found advantageous to form the calcium soap in Thus, a preferred method of preparation calls for In comparing Examples Nos. 1 and 2, it is noted that the use of calcium stearate in conjunction with calcium sulfonate has raised the viscosity from 337 to 481 S.U.S. at 100 R, an increase of 144 seconds, although stability is somewhat improved. A similar viscosity increase is shown in the case of Example 3, using behenic acid, although stability at elevated temperature shows a very marked improvement over 1. Examples Nos. 4

dissolving or dispersing the lime in the water and mixing and 5 indicate the eifects obtained when naphthenic acids are substituted for aliphatic acids. Naphthenic acid, with a molecular weight of 295 which is somewhat above the molecular weight of conventional naphthenic acids (Example 4), yields an acceptable viscosity, but the emulsion is unstable. In contrast, Example 5 shows the naphthenic acid with a molecular weight of 415, while yielding a similar viscosity, provides a product of substantial heat stability.

Examples 6 through 8 indicate the unusual improve ments brought about when calcium sulfonate is used in conjunction with two stabilizers, one the calcium salt of an aliphatic acid, the other the calcium salt of a suitable naphthenic acid (e.g. molecular weight 415). In Example No. 6, using stearic acid, a viscosity below 350 seconds is obtained, and stability at 170 F. is quite good although at 200 F. the product still exhibits deficiencies. A radical further improvement in stability is brought about when behenic acid is substituted for stearic acid, as indicated in Example 7. Combined separation of water and oil, both at 170 F. and 200 F., amounts to less than 12% of total volume while the emulsion retains essentially the same viscosity. Such stability is particularly noteworthy at 200 F. since this temperature approaches the boiling point of water, an essential constituent of the emulsion.

Example 8 is identical with Example 7 with respect to composition, but differs in the method of mechanical treatment. Ordinarily, homogenizing treatment tends to reduce particle size of the dispersed phase which in turn increases the viscosity of the emulsion. It is surprising, therefore, that homogenizing brings about a further reduction in viscosity without affecting the stability of this composition.

The detailed description of the invention given hereinabove and the examples supplied are not intended to limit the scope of this invention. The only limitations intended are those found in the claims attached hereto.

I claim:

1. A composition for use as hydraulic fluid consisting essentially of a water-in-oil emulsion containing about 0.25-2.50 percent by weight of oil-soluble calcium petroleum sulfonate having a molecular weight of at least 900 as an emulsifying agent and about 0.1-2.50 percent by weight of calcium salts of aliphatic acids having carbon chain length of about G -C and about 0.1-2.50 percent by weight of calcium salts of naphthenic acids having molecular Weights of about 315-1000, the oil portion of said emulsion being a hydrocarbon oil having a viscosity range of about 50-400 Saybolt Universal seconds at 100 F.

2. A composition for use as hydraulic fiuid consisting essentially of water-in-oil emulsion in which about -50 percent by weight of the mixture is water uniformly distributed in fine particle form and containing about 0.25-2.50 percent by weight of oil-soluble calcium petroleum sulfonate having a molecular weight of at least 900 as an emulsifying agent and about 0.1-2.50 percent by weight of calcium salts of aliphatic acids having carbon chains of about 0 -0 and about 0.1-2.50 percent by weight of calcium salts of naphthenic acids having molecular weights of about 315-1000, as a combined stabilizing medium, whereby the emulsion is retained with the water particles in fine particle form and uniformly distributed throughout the mixture, the oil portion of said emulsion being a hydrocarbon oil having a viscosity range of about 50-400 Saybolt Universal seconds at F.

3. A composition for use as hydraulic fluid consisting essentially of a water-in-oil emulsion in which about 10-40 percent by weight of the mixture is water uniformly distributed in fine particle form and containing about 0.25-2.50 percent by weight of oil-soluble calcium petroleum sulfonate having a molecular weight of at least 900 as an emulsifying agent and a mixture of 0.2-1.0 percent by weight of the calcium salts of aliphatic acids having carbon chains of about C -C with 0.2-1.0 percent by weight of the calcium salts of naphthenic acids having molecular weights of about 315-500 as a stabilizing medium, the oil portion of said emulsion being a hydrocarbon oil having a viscosity range of about 50- 400 Saybolt Universal seconds at 100 F., whereby the emulsion is retained with the water particles in fine dispersion in the oil.

4. A composition for use as hydraulic fluid consisting essentially of a water-in-oil emulsion in which about 10-40 percent by weight of the mixture is water uniformly distributed in fine particle form, the oil is a white oil having a viscosity of about 50-400 Saybolt Universal seconds at 100 F. and the mixture contains about 0.3- 1.0 percent by weight of oil-soluble calcium petroleum sulfonate having a molecular Weight of at least 900 as an emulsifying agent and a mixture of about 0.2-1.0 percent by weight of a mixture of the calcium salt of behenic acid in nearly equal proportion with 0.2-1.0 percent by weight of calcium salt of a naphthenic acid having a molecular weight of 415, as a stabilizing medium, whereby the emulsion is retained with the water particles in fine dispersion in the oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,632,734 Nunn Mar. 24, 1953 2,744,870 Stillebroer May 8, 1956 2,820,007 Van Der Minne et al. Jan. 14, 1958 2,856,362 Morway Oct. 14, 1958 2,907,714 Francis et al. Oct. 6, 1959 2,927,079 Jense et al. Mar. 1, 1960 2,961,404 Francis Nov. 22, 1960 3,019,190 Holzinger Jan. 30, 1962

Claims

1. A COMPOSITION FOR USE AS HYDRAULIC FLUID CONSISTING ESSENTIALLY OF A WATER-IN-OIL EMULSION CONTAINING ABOUT 0.25-2.50 PERCENT BY WEIGHT OF OIL SOLUBLE CALCIUM PETROLEUM SULFONATE HAVING A MOLECULAR WEIGHT OF AT LEAST 900 AS AN EMULSIFYING AGENT AND ABOUT 0.1-2.50 PERCENT BY WEIGHT OF CALCIUM SALTS OF ALIPHATIC ACIDS HAVING CARBON CHAIN LENGTH OF ABOUT C16-C30 AND ABOUT 0.1-2.50 PERCENT BY WEIGHT OF CALCIUM SALTS OF NAPHTHENIC ACIDS HAVING MOLECULAR WEIGHTS OF ABOUT 315-1000, THE OIL PORTION OF SAID EMULSION BEING A HYDROCARBON OIL HAVING A VISCOSITY RANGE OF ABOUT 50-400 SAYBOLT UNIVERSAL SECONDS AT 100*F.